This week in animal research 110915

Today 9 in 10 cancer deaths are caused by the disease spreading – or metastasis - to other areas of the body. However, a new small sponge-like implant can mop up cancer cells as they move through the body, according to a study in mice. The device could act as an early warning system in patients, alerting doctors to cancer spread. The implant also seems to stop rogue cancer cells reaching other areas where new tumours could grow.

Hawks employ a swooping on prey approach to hunting like jays horizontally or from higher up. As a result, jays stay away from a zone spreading out and down from the top of any tree where hawks are nesting. Jays are agile and can hop around in foliage to rob hummingbird nests, so the hawks’ presence effectively envelops the hummingbirds in a cone-shaped force field that keeps their eggs safe.

The differences between cancerous and normal cells are often so minimal that they are extremely hard to tell apart during surgery. There are several imaging technologies that help surgeons see inside the body before they cut, many of which were developed to help diagnose cancer, but they are still not precise enough, especially when it comes to brain tumours. One new technique promises to make a major difference in this field of operation: tumour paint. Researchers found that a neurotoxin – chlorotoxin – extracted from the venom of one of the deadliest scorpions in the world, the deathstalker, accumulates in tumours, and only tumours, in the brains of mice. It also showed a remarkable ability to pass into the brain, unobstructed by the blood-brain barrier. By using a synthetic version of the chlorotoxin and attaching a fluorescent molecule, they produced a substance that could light up tumour cells. During preclinical trials with mice and dogs that took place between 2005 and 2011, tumour paint proved to be more than 5,000 times more sensitive than MRI and is currently undergoing clinical trials.

Cartilage promotes low-friction movement and helps bones glide pain-free through a wide range of motion and many functions. When cartilage degrades, a host of problems can emerge because of its limited ability for self-healing or repair. Understanding the biomechanics of natural cartilage could lead to the development of better artificial joint implants. The team studied kangaroo cartilage as an analogue for human tissue, and found that a network of collagen protein close to the surface played an important role in helping the cartilage absorb forces without damaging – a finding that could help improve joint implants. The kangaroo is a suitable alternative animal model for the study of human shoulder cartilage biomechanics because the kangaroo has a bidpedal posture, is similar in size to a human and the kangaroo's grabbing, punching and lifting limb action resembles human shoulder-mediated movements. Sheep, certain rats or mice species, or non-human primates are typically studied as animal models, but lack many of these human-like characteristics.

People may have contracted Alzheimer’s disease during certain medical procedures, the same way as mad-cow disease. Animal studies support the idea that amyloid plaques - a tell-tale sign of the disease - could be spread accidentally during medical and surgical procedures in the same way as CJD, via contaminating protein "seeds" or prions that grow in the brain. One of these treatments called human growth hormone injections was withdrawn in the UK in 1985 once the risk of Creutzfeldt-Jakob disease infection became clear. However, there still needs more proof to assess where these results are accurate and universal – Alzheimer’s remains a disease that is not ‘caught’ like a cold.

Scientists have discovered the first example of a protein that causes muscle weakness and loss during aging. It alters gene expression in skeletal muscle, causing reduction of muscle protein synthesis, strength, and mass. The researchers have also identifies two compounds, one in green tomatoes and the other in apples that reduces the acute muscle wasting caused by starvation and inactivity due to the protein in aged skeletal muscle. The study could lead to new therapies for age-related muscle weakness and atrophy.